Ever wondered what's involved in a sleep apnea test? Dr. Max Hirshkowitz answers our basic questions about sleep tests and lets us know what to expect during and after the test. Dr. Hirshkowitz is an Associate Professor at Baylor College of Medicine and Director of the Sleep Disorders and Research Center of the Houston Veterans Affairs Medical Center. He has lectured on sleep disorders throughout the world and is the author of Sleep Disorders for Dummies.
Interview with Dr. Max Hirshkowitz, Sleep Expert
What is a sleep study? Why would a doctor order a sleep study to be done?
There are several types of sleep studies. The traditional sleep study involves recording brain activity, eye movements, muscle tone, breathing (airflow and breathing effort), leg movement, heart rhythm, blood oxygen level, and body position. The recording, called a polysomnogram, typically is performed in a laboratory and involves an overnight session. The polysomnogram is used to evaluate sleep in an individual who sleeps poorly, has daytime sleepiness (even when not sleep deprived), or has abnormal sleep-wake symptoms (for example, sleepwalking, nightmares, or other unusual behaviors during sleep). The most common purpose use of sleep studies is to diagnose sleep-related breathing disorders.
How and where is a sleep study performed? What is a sleep lab? Can it be done at home?
Sleep studies are usually performed in a specialized laboratory. This laboratory can be in a hospital or in a free-standing clinic. The bedrooms are private and typically furnished to appear similar to a bedroom or hotel room. Specialized recording equipment is located in a central "control room" that is connected to a panel in the bedroom. If an individual has clear signs of a sleep-related breathing disorder, an abbreviated test is sometimes performed in the home. This type of "home sleep test" usually records breathing, heart rhythm, snoring, and blood oxygen levels. Sleep studies should be performed according to a person's usual schedule.
If you work nights, can a sleep study be done during the day?
If the individual being tested is a night shift worker, studies should be performed during the day at the time they usually sleep. Many laboratories cannot accommodate this requirement; but, to do a proper assessment, this is important.
What are the types of sleep studies?
Sleep studies types include:
- Attended, laboratory baseline studies - Used to diagnose sleep disorders
- Positive airway pressure therapy titration studies - Used to determine how much positive pressure is needed to treat a sleep-related breathing disorder
- A combination of the above studies, called a split-night study - Used to first diagnose a sleep-related breathing disorder and then attempt to find a positive airway pressure adequate to treat that disorder
- A multiple sleep latency test - A series of four or five, 20 to 40-minute nap opportunities scheduled at 2-hour intervals during the day used to diagnose a sleep disorder called narcolepsy
- A maintenance of wakefulness test - A series of four, 40-minute test sessions scheduled at 2-hour intervals during the day used to see if a person has overwhelming sleepiness and cannot stay awake in a non-stimulating situation
- A home sleep test - Used to confirm a high clinical suspicion that an individual has a sleep-related breathing disorder.
What can a person expect during a sleep apnea test? Is there any discomfort?
When a person has a sleep study, electrodes are placed on the scalp, face, neck, chest, and legs. These electrodes are attached with a gooey paste. Other sensors are attached near the nose (and/or mouth), on the ear (or finger tip), rib cage and abdomen. All of these devices are "non-invasive," meaning that the skin is not broken and blood is not drawn. The monitoring devices can be somewhat uncomfortable but should not hurt.
What if you have trouble sleeping or you need to get up to use the restroom?
Individuals may have trouble sleeping with all of the recording devices and because they are in a strange (new) environment. Most people are able to sleep after initial difficulty. In fact, many patients tested in sleep laboratories have excessive sleepiness and experience little or no difficulty sleeping due to the wires, monitoring devices, and novel environment. If a person needs to use the restroom, they can call out to the technician who is there all night monitoring their sleep. The technician can either unplug them or give them a urinal, as needed.
What happens after the test?
After the test is completed, the individual completes a questionnaire that asks them about their sleep that night. Every page of the sleep study is then scored by a technologist for sleep stages, movements, and breathing events. Any unusual brainwave or heart rhythm activity is noted. The recording is then reviewed by a sleep specialist who interprets the sleep study, correlates the findings with the person's sleep-wake problems, makes a clinical diagnosis, and formulates a treatment plan. Depending upon what sort of sleep disorder is found, the individual should then be scheduled for either:
- A follow-up visit at the clinic to discuss the results and/or possible treatment
- Further sleep testing
A sleep apnea test or any sleep study is an excellent diagnostic tool for sleep disorders. If you feel that you may have a sleep disorder, be sure to consult with your doctor. A test of this type could be a key step in improving your sleep and your health.